Since photographic light-sensitive materials are generally composed of an electrically insulating base and a photographic layer, electrostatic charge is often accumulated by contact friction between the same substances or different substances or by separation thereof in the step of production of the photographic light-sensitive material or in the case of using it. The accumulated electrostatic charge causes many troubles. The most serious trouble is formation of dotted spots or branched or feathery line specks in the case of developing the exposed photographic film, because of the discharging of the accumulated electrostatic charge. This trouble is the so-called static mark, by which commercial value of the photographic films is greatly damaged and is sometimes lost. It will be easily recognized that very dangerous consequences can arise when such appears on, for example, medical or industrial X-ray films and the like. This phenomenon is a very troublesome problem, because it is not seen until development is carried out. Further, the accumulated electrostatic charge becomes a cause of inducing a secondary problem in that dust adheres to the surface of the films or uniform coating cannot be carried out.
The electrostatic charge is frequently accumulated, as described above, in the case of producing or using the photographic light-sensitive materials. For example, in the step of production, it is generated by contact friction between the photographic film and rollers or by separation of the emulsion face from the base face in the step of winding or rewinding the photographic film. Further, it is generated by contact with or separation from mechanical parts or fluorescent sensitizing paper in an automatic camera for X-ray films. In the case of photocomposing films or photocomposing papers, it is generated by contact with or separation from rollers made of rubber, metal or plastics, etc., in a computer photocomposing machine or a glass plate on CRT. In addition, it is generated by contact with packing materials. The static mark on the photographic light-sensitive materials derived by accumulation of the electrostatic charge becomes remarkable with an increase of sensitivity of the photographic light-sensitive material and an increase of the processing rate. Particularly, in recent years, generation of the static mark is more easily caused because the photographic light-sensitive materials are highly sensitized and there are many opportunities of being subject to severe handling such as high speed coating, high speed photographing or high speed automatic processing, etc.
In order to remove these troubles due to electrostatic charge, it is preferred to add an antistatic agent to the photographic light-sensitive materials. However, antistatic agents used conventionally in other fields cannot be used as antistatic agents for photographic light-sensitive materials since they are subject to various restrictions for photographic light-sensitive materials. Namely, an antistatic agent for use with a photographic light-sensitive material is required to have not only excellent antistatic properties but also performances such that it does not have a bad influence upon the photographic characteristics, for example, sensitivity, fog, granularity and sharpness, etc., of the photographic light-sensitive materials; it does not have a bad influence upon the film strength of the photographic light-sensitive materials (namely, the film is not easily injured by rubbing or scratching); it does not have a bad influence upon adhesive resistance (namely, the photographic light-sensitive material does not easily adhere to the surface each other or to the surface of another substance); it does not accelerate fatigue of processing solutions for the photographic light-sensitive materials; and it does not deteriorate the adhesive strength between constituent layers in the photographic light-sensitive material. Accordingly, it is subject to many restrictions in order to apply the antistatic agent to the photographic light-sensitive materials.
A way to remove problems caused by static electricity is to increase the electrical conductivity of the surface of the light-sensitive material so that the electrostatic charge disappears within a short time prior to discharging the accumulated electric charge.
Therefore, it has been considered hitherto to improve the conductivity of the base of the photographic light-sensitive materials or various kinds of coating surface layer thereof, and it has been attempted to utilize various hygroscopic substances or water-soluble inorganic salts, and certain kinds of surface active agents and polymers, etc. For example, it has been known to use polymers as described in U.S. Pat. Nos. 2,882,157, 2,972,535, 3,062,785, 3,262,807, 3,514,291, 3,615,531, 3,753,716, 2,938,999, etc., surface active agents as described in U.S. Pat. Nos. 2,982,651, 3,428,456, 3,457,076, 3,454,625, 3,552,972, 3,655,387, etc., and metal oxides and colloidal silica as described in U.S. Pat. Nos. 3,062,700, 3,245,833, 3,525,621, etc.
However, many of these substances show singularity to species of the film base or difference of photographic composition. Namely, there is a case that though it shows a good result in a certain kind of film base or photographic emulsion or a certain kind of photographic constituent element, but it does not serve for preventing generation of static electricity in another film base or photographic constituent element and has a bad influence upon the photographic properties.
On the other hand, there are many cases that, though the antistatic effect is very excellent, it cannot be used, because of having a bad influence upon photographic characteristics such as sensitivity, fog, granularity or sharpness, etc., of the photographic emulsion.
Accordingly, it is very difficult to apply the antistatic agents to photographic light-sensitive materials and use of them is often restricted to a certain region.
Nonionic surface active agents having a polyoxyethylene chain in the molecule described in British Pat. No. 861,134 and German Pat. No. 1,422,809 are known to have an excellent antistatic property.
On the other hand, the photographic light-sensitive materials are frequently subject to the undesirable influence of touching with a photographic apparatus such as various devices, machines or cameras, etc., or contact friction by adhesion materials such as dust or fibrous waste, etc., or contact friction of the photographic light-sensitive materials themselves, such as contact friction between the surface of the sensitive material and the back face in the case of handling such as rewinding or transferring in photographing, development processing, printing or projection, etc., including the step of production such as coating, drying or processing, etc.
For example, there is deterioration of the moving property of the sensitive material in the camera or other apparatus, or formation of waste of film in the camera or other apparatus.
Hitherto, various processes have been proposed in order to produce photographic light-sensitive materials having improved physical properties wherein the slipping friction of the photographic light-sensitive material is reduced so that the photographic light-sensitive material smoothly moves in a film magazine, a camera gate or a projector gate, etc.
For example, a process which comprises incorporating dimethylsilicone and a specified surface active agent together in a photographic emulsion layer or a protective layer to give a slipping property to the photographic film as described in U.S. Pat. No. 3,042,522, a process which comprises applying a mixture of dimethylsilicone and diphenylsilicone to the back face of the photographic film to give a slipping property as described in U.S. Pat. No. 3,080,317, and a process which comprises incorporating triphenyl end blocked methylphenylsilicone in a protective layer to give a slipping property to the photographic film as described in British Pat. No. 1,143,118 have been known.
However, since these compounds (polyoxyethylene type surface active agent or silicone type slipping agent) are localized in the surface and they are transferred so that they deteriorate the surface properties of the sensitive material when the sensitive material is brought in contact with another different material for a long time. Particularly, in the case of a photographic sensitive material having a hydrophilic colloid backing layer, the polyoxyethylene type surface active agent or the silicone type slipping agent incorporated in the emulsion protective layer is transferred to the backing layer during preservation by which the backing layer and the emulsion protective layer acquire electrification characteristics and slipping properties different from the prescribed surface properties. Consequently, the antistatic property and the slipping property remarkably deteriorate.